2.0 Analysis 2.1 General Communications In this occurrence, a telephone communication between the officer in charge (OIC) of loading/deballasting and the engine room staff was not formally reiterated. There is a time interval between the commencement of pumping ballast and the time when a watchman takes a water level reading from a respective tank. If there are 10 - 14 ballast tanks to be read, it is possible that it may be some time before a tank pumping sequence error is detected and the OIC is informed. A formal, handwritten instruction may be the surest method for ensuring that a critical operation is carried out; on many ships, this is standard procedure for ballasting operations. In the case of a telephone instruction, if that instruction is repeated by the receiving party, the person issuing the order knows immediately if the order has been understood and can expect that it will be acted upon. Further, when the person carrying out the action confirms that it has been done, a second confirmation of the original order is completed. 2.2 Communications and Coordination - Loading/Deballasting While loading was in progress, verbal instructions given to engine room staff to deballast were acknowledged, recorded, and carried out, but there was no corroboration from the engine room when the tanks had been emptied or pumped down. Most of the communication was one-way, from the deck to the engine room, with very little feedback. This lack of follow-up meant that the OIC ordering the deballasting of the vessel could only keep current of the vessel condition by noting physical tank soundings some time later, after pumping had commenced. The result was that the vessel was subjected to bending moments that were markedly higher than the maximum permissible. This situation could have been avoided if more formal communications had been used and the agreed deballasting/loading plan was adhered to. When the master returned to the vessel, some two hours prior to the occurrence, deviation from the loading plan and pumping sequence caused him some concern, but he indicated that he had faith in his officer's abilities. However, had the vessel's loaded condition been reassessed at that time, and appropriate corrective action been taken, the occurrence may have been prevented. 2.3 Loading and Deballasting To minimize structural stress, cargo should be loaded and a similar weight of appropriately located water ballast discharged concurrently, (this is not always possible, given the rate at which bulk cargoes are loaded) and particular attention must be paid to the sequence of loading and deballasting. Shortly before the hull failure, the loading was almost completed in hold No1 and it contained approximately 4923tons of cargo. Port and starboard (P S) ballast tanks No2 were nearly empty and there was no cargo in hold No2. The total weight and distribution of cargo, in conjunction with no loading in way of cargo hold No2, contributed significantly to a bending moment on the hull girder of approximately 2.3times the maximum permissible. At 2035, loading of cargo into hatch nos19, 20, and21 was completed. The OIC deviated for the first time from the planned loading sequence and directed the shore rig to load HL1 aggregates into hatch No9 instead of hatch No13. This initial departure from the intended loading/ deballasting sequence led to complications and called for further deviations which eventually caused stresses that the hull could not withstand. Deviations from the loading sequence, combined with a lack of appropriate compensatory ballasting measures to minimize hull stresses, caused the vessel to hog. The mechanical failure of the bottom structure occurred when compressive stress exceeded the critical buckling stress of the bottom structure. This caused extensive buckling and tensile fracturing of the adjacent structure, which culminated in the loss of longitudinal hull integrity. 2.4 Determination of Draughts Factors affecting an accurate reading of the vessel's draught marks during loading were as follows: cold weather, poor lighting, driving rain, darkness, and a flashlight with reportedly insufficient candle power. The distance from the shoreline, where the draught was read, to the ship side markings at the stern was over 30metres. At the bow, this distance was approximately 25metres. Because of changes in the accepted loading plan, close and frequent monitoring of draught marks forward, midship, and aft was necessary. For the majority of the loading period, weather was not a factor. As the weather deteriorated, the distance from the shore and the type of flashlight available made draught monitoring difficult; consequently, accurate readings were not obtainable. Although the OIC of loading/deballasting believed that the vessel was hogged nine inches at the time of the occurrence, subsequent calculations indicate that the actual hog was significantly greater. Because of the difficulty of reading draught marks in prevailing conditions, the rate at which the cargo was loaded and the frequency of reading the draughts, the extent of deflection was not determined before the hull girder was overstressed. 2.5 Condition of the Bottom Alongside the Berth The possibility that the vessel could have suffered localised distortions and fractures due to obstructions on the harbour bottom alongside the berth was examined. A hydrographic survey of the area was last conducted in September1997. On 10July2000, divers conducted a localised survey to assess the depth and condition of the bottom. The survey found no features to indicate uncharted obstructions, boulders, or other features that could have caused bottom shell damage and contributed to the initiation of the hull failure. Furthermore, review of the mining company's ship loading record before June2000 indicated that vessels had loaded at the berth to a departure draught deeper than that of the Algowood, and there were no reports of these ships having suffered damage as a result. 2.6 Officers' Knowledge of Structural Stresses In 1998, Transport Canada Marine Safety (TCMS) published The Examination and Certification of Seafarers (TP2293). These standards are intended as a guide for the certification of officers on ships, reflecting the requirements of the Marine Certification and Crewing Regulations. Examination requirements of these standards, for a master local voyage, address requirements for ship construction and engineering, including the following: Structures and Construction Methods Knowledge of structural stresses; difference between stress and strain; sheer force and bending moments and interpretation of graphical solutions;...reasons for extra strengthening;...special construction features of VLCCs [very large crude carrier] and special methods employed to ensure adequate longitudinal and transverse strength; special construction features of oil/bulk/ore carriers.13 Stresses in Ships Knowledge of predominant stresses when unloading bulk carriers with grabs and by uneven off-loading; predominant stresses on bulk carriers when loading concentrates or other bulk products at a high rate; uneven distribution of cargo; heavy weights on deck or tank tops; stresses on hull caused by motion of a vessel at sea, including panting, pounding, hogging, sagging and racking; structural stresses when grounded. The master and first mate held valid certificates for their positions and had passed examinations for each of the required subjects for that class of voyage, including the examination for ship construction and engineering. Post-occurrence calculations, based on the intended loading plan, indicate the vessel would have been subjected to a SWBM 1.9times that of the maximum approved level. In the absence of any prior calculations to determine the relative SWBM for the intended loading condition, neither the ship nor the company operating personnel were aware of its magnitude. 2.7 Existing Safety Measures for Bulk Carriers Canada's bulk carrier fleet comprises some 70vessels, which have an average age of over 33years. Because of their particular service, bulk carriers operating exclusively on the Great Lakes are not required to conform to the more stringent requirements for ocean-going vessels and have especially reduced structural, scantling, and load line standards. However, basic principles of hull bending stress distribution are still applicable and, because of a bulk carriers' greater length-to-beam proportions, special attention is required during loading and unloading operations to ensure that excessively high stressing does not occur. A review of structural failures history in Canada suggests that the probability of a catastrophic failure is minimal, but the consequences on people, property, and environment are considerable. Therefore, this small probability presents an undesirable risk which can be easily managed, using proven cargo loading practices to keep deck/bottom stresses within acceptable limits. The International Maritime Organization (IMO), recognizing a need to improve the safe loading and unloading of bulk carriers engaged on international voyages, has amended the International Convention for the Safety of Life at Sea (SOLAS) by adding safety measures for bulk carriers. In particular, Chapter XII, Regulation 11 of SOLAS, addresses the loading of bulk carriers at least 150 metres long. This regulation requires that bulk carriers be fitted with loading instruments capable of providing information on hull girder shear forces and bending moments. It is recognised that the loading instrument is a necessary tool to more efficiently ensure that hull girder shear forces and bending moments are kept within permissible limits during, and at the conclusion of, loading or discharging operations. Although a loading instrument is not a regulatory requirement aboard Great Lakes bulk carriers, TCMS encourages the installation of such instruments. The IMO has also adopted the Code of Practice for the Safe Loading and Unloading of Bulk Carriers to assist masters and officers in ensuring a safe operating environment. 3.0 Conclusions 3.1 Findings as to Causes and Contributing Factors The intended loading and deballasting sequence was not adhered to and the vessel was subjected to excessive bending stress which resulted in structural failure of the hull. The disposition of the cargo and ballast at the time of the failure caused a still water bending moment about 2.3 times the maximum permissible. A lack of feedback communication, after deballasting instructions had been given, resulted in the OIC not being kept current with the progress of deballasting. The frequency and accuracy with which the draught marks were read during loading were insufficient to closely monitor the hogging of the hull. Draught mark readings became estimates as the weather deteriorated and not all means available to assist in accurately reading draughts were utilized. The magnitude of the stresses imposed on the Algowood, as a result of deviating from the intended loading sequence, were not known nor appreciated by shipboard personnel. 3.2 Findings as to Risk Neither the ship nor company operational personnel were aware that the stresses that would have been imposed on the vessel by the intended loading plan, were 1.9 times the maximum permissible SWBM approved by Lloyd's. 3.3 Other Findings Laboratory examination determined that samples of steel taken from the area of structural failure had no abnormalities which adversely affected weldability and had tensile properties and notch-toughness characteristics comparable to those of Lloyd's Grade A steel. None of the recorded material thickness wastage readings exceeded accepted limits at which replacement of the material would have been required. A post-occurrence survey of the bottom alongside the berth confirmed that there were no uncharted obstructions, boulders, or other features that could have contributed to the initiation of the hull failure. The ship's approved loading manual on board the vessel contains representative loading conditions but does not outline loading and deballasting sequences. 4.0 Safety Action 4.1 Action Taken As a result of this occurrence, Algoma Central Marine has initiated a review of its practices and procedures and has taken the following actions: Immediately following the incident, the company modified its cargo handling policy to put in place procedures that require all split loading and unloading to be reviewed by the company's naval architects to determine if the proposed load/unload falls within the allowable limits set for various vessels with respect to stress and shear forces. A training course was developed by the company's naval architects, addressing stresses and strains that occur on vessels during cargo handling operations. This seminar was presented to all masters and chief officers in the winter of 2000. A copy of this information was given to all participants and copies were sent to all vessels for junior officers to review. The company was investigating requirements for Stress and Stability Computers (loading instruments) prior to the incident in Bruce Mines. Subsequent to the incident, the company has contracted with a firm to develop and install loading computers in its fleet. Installation of these systems started in the fall of 2001 and should be completed by the summer of 2003. A review of past cargo handling practices was carried out on a sample of the company's fleet to determine if practices similar to those that took place on the Algowood were occurring on other Algoma ships. This review found no significant occurrences where a vessel's allowable SWBM had been exceeded. The company contracted with a marine consultant to perform an audit on company cargo handling procedures. Results of this audit were reviewed with management and led to development of the training program outlined above. A condition survey was carried out on all company vessels to determine if any structural deficiencies are occurring in the area where the Algowood failed. These surveys found no evidence of structural deficiencies in any of the vessels. 4.2 Safety Action Required Loading information Because of their particular service, bulk carriers operating exclusively on the Great Lakes are not required to conform to the more stringent requirements for ocean-going vessels and have especially reduced structural, scantling, and load line standards. However, basic principles of hull bending stress distribution are still applicable and, because of bulk carriers' greater length-to-beam proportions, special attention is required during loading and unloading operations to ensure that excessively high stressing does not occur. The Canadian Load Line Regulations (Inland) require that the master of every ship shall be supplied with sufficient information, in an approved form, to enable him to arrange for the loading and ballasting of his ship in such a way as to avoid the creation of unacceptable stresses in the ship's structure. Loading manuals onboard Canadian vessels provide masters with guidelines to assist them in ensuring that their vessels are safely ballasted and trimmed throughout a voyage, to maintain adequate structural integrity in port and in various operating conditions. The Algowood approved vessel's Loading Manual made reference to acceptable shear forces and bending moments for various loading conditions. However, these manuals do not address the vessel's loading sequence which, in this occurrence, led to complications which eventually caused stresses that the hull could not withstand. It is possible, by improper distribution of loading, to highly stress the structure locally (under the load) and/or the basic longitudinal hull girder. Since the structural arrangements may vary greatly, the limitations associated with setting out exact rules for the distribution of loading in all ships have been recognized by International Maritime Organization (IMO). Toward this end, IMO14 requires that bulk carriers engaged on international voyages be fitted with loading instruments capable of providing information on hull girder shear forces and bending moments. This provides the master with accurate and timely information on hull girder shear forces and bending moments to assist in preventing overstressing of the ship's structure. Although the Algowood was in class and had passed all regulatory inspections, the Board is concerned that Canada's ageing bulk carrier fleet of some 70registered ships, is vulnerable to structural failures with serious consequences. The Board is concerned that mariners may not fully appreciate that deviation from approved loading manuals and loading plans may overstress the structure and lead to catastrophic failures, in particular, the adverse consequences on the hull caused by the disposition of the cargo and ballast during loading operations. Overstressing of the hull may not be immediately evident during loading/discharging and could become manifested after the vessel leaves port and is at sea. Such failures could result in the loss of the vessel, cause extensive pollution, and also put the crew at serious risk, depending upon the circumstances at the time. The Board believes that comprehensive loading and unloading information will help masters to arrange the loading and unloading so as not to overstress the structure. Therefore, the Board recommends that: The Department of Transport require that masters on all Canadian bulk carriers of 150 m in length and over have continuous access to on-board or company shore-based hull stress monitoring systems to help ensure that maximum allowable hull girder stresses are not exceeded.